Forced Response Variation of a Compressor Utilizing Blade Tip Timing, Strain Gages, and As-Manufactured Finite Element Models

Abstract

The dynamic response of turbine engine components varies widely due to manufacturing deviations in the blades known as mistuning. This dynamic variation is investigated using a single-stage compressor experimentally using both blade tip timing (BTT) and strain gage (SG) measurements and using as-manufactured finite element models (AMMs) on a first bend mode. Operational BTT and SG safety limits were generated using both averaged and AMM models via Goodman material properties. The predicted individual blade stress/deflection (S/D) ratios and strain gage ratios for this mode will be compared to the average finite element counterparts. Additionally, the correlation between BTT and SGs will be presented. This correlation will be performed using two approaches: blade maximum stress comparisons and measured response compared to the sensors safety limits. It will be shown that accounting for geometry with AMMs produces more accurate strain gage to BTT correlation compared to average models. An experimental model updating procedure is developed to increase the strain gage to BTT correlation by optimizing the location the BTT optical spot probes measure on the blade chord. Implementing this procedure using as-manufactured models is able to improve strain gage to BTT correlation.